Apparatus and method for reducing drag of a bluff body in ground effect using counter-rotating vortex pairs

A method of reducing aerodynamic base drag of a bluff body vehicle moving in close proximity to a ground plane in a flowstream substantially parallel to a longitudinal centerline of the bluff body, said bluff body having a base surface at a trailing end thereof, said method comprising:

• providing alongside the vehicle upstream of the base surface a pair of lift surfaces extending to lift surface tips, said pair of lift surfaces capable of inducing generation of a pair of counter-rotating trailing vortices when in the flowstream, and said lift surface tips substantially near the bluff body to confluence the vortices downstream in the wake of the vehicle in a direction substantially orthogonal to the flowstream, wherein said confluence draws the flowstream in and around behind the trailing end to raise the pressure on the base surface and reduce the aerodynamic base drag.

A method of reducing aerodynamic drag of a bluff body in a flowstream substantially parallel to the longitudinal centerline of the bluff body, said method comprising:

• generating at least one pair of counter-rotating vortices alongside the bluff body to induce downstream confluence of said vortices in the wake of the bluff body in a direction substantially orthogonal to the flowstream, whereby the confluence draws the flowstream down and around a trailing end of the bluff body to raise the pressure in a recirculation zone thereof and reduce the aerodynamic base drag.